1. Field of the invention
The invention relates to a rectangular ceiling tile to be supported in an exposed type suspended grid system of perpendicularly crossing girders of inverted T-profile.
2. Description of the Prior Art
The tile is of the kind comprising a core of fiber material with two opposite first edges forming each a stepped groove having a deeper section and a shallower section, and two opposite second edges forming each a recess, the tile forming a projecting circumferential rim on the lower face thereof along said first and second edges.
When the tile is mounted in the grid system the flanges of the girders extending along said first edges are received by the shallower section of the stepped grooves and support the tile in the grid system, the circumferential rim of the tile leaving the flanges of the grid exposed to view. The tiles are mounted and demounted by lifting and displacing the tile so that the flange at one of said first edges will be received by the deeper section and the other one of said first edges will clear the adjacent flange.
A ceiling suspension system of this type is disclosed in GB-B-2,200,151.
Problem involved
When the tiles are positioned in the supporting grid system the clearance between the tiles and the grid system must be minimized so that the tile cannot take a skew position in the grid system, but on the other hand the clearance cannot be made to small because then the tile will be very difficult to mount and demount particularly if the grid system does not include accurately right angles between the crossing girders.
Moreover, the edge surfaces of the tile can be often rough and coarse so that the friction between the edge surfaces at said second edges and the girders is considerable and impairs the movement of the tile in relation to the grid system at mounting and demounting.
The said two requirements, xe2x80x9cpositioningxe2x80x9d and xe2x80x9cmounting/demountingxe2x80x9d, contrast to each other, and the problem is to find a compromise therebetween.
The problem is solved according to the invention by providing a rectangular ceiling tile to be supported in an exposed type suspended grid system of perpendicularly crossing girders of inverted T-profile, said tile comprising a core of fiber material with two opposite first edges forming each a stepped groove having a deeper section and a shallower section, and two opposite second edges forming each a recess, the tile forming a projecting circumferential rim on the lower face thereof along said first and second edges, and at least one metal or plastic element inserted into the fiber material of the core in a transverse edge surface thereof and forming a protruding ridge, extending transversely of the tile.
By this arrangement mounting and demounting of the tile can easily be effected since the friction between the metal or plastic element and the flanges of the grid system will be very low. Tolerances of the tile and/or the flanges of the grid system will be effectively compensated for automatically and unnoticeably by the metal or plastic element being resiliently pressed into the fiber material of the core of the tile at mounting.
The tile of the invention provides a regular and linear rectangular pattern on the lower side of the suspended ceiling, and the tile is fixedly supported by the grid system, which excludes any disturbance of the regularity of the pattern on the lower side of the ceiling.
In one preferred embodiment of the invention the element comprises a U-shaped staple made of aluminum the limbs of which are inserted into the core of the tile and the web of which forms said protruding ridge.
In another preferred embodiment of the invention the element comprises a plate forming at least one lug which is inserted into said core, and at least one linear depression which forms said protruding ridge. In this embodiment the plate may be made integral with a tongue forming an edge clip for engagement with a girder received in said recess.